I'm having trouble with my L4D dedicated server, I'll try and post as much info as possible so bare with me

I started off running it on a Pentium III coppermine with 320 MB of RAM and got about 20FPS, I didn't expect much better. So I moved it over to a Pentium 4 Northwood @ 2.4 GHz with 512 MB of RAM, now I'm getting 27FPS....

Being a server the kernel (2.6.18) was set with 100Hz timer frequency with no preemption. After reading around this site I found that 1000Hz with preemption was better, and recompiled a new 2.6.27 kernel. Now I'm getting 30FPS....

Most of my users are experiencing 200+ ping, traceroute to their IP reveals ~70ms latency to the last router hop. My connection is not optimal, but I am able to host co-op from my desktop with no lag over the same connection.